Technical Field
The present invention generally relates to systems and methods for power detection.
Description of Related Art
Radio Frequency (RF) power amplifiers are used in communication devices such as cellular telephones, smart phones, personal digital assistants (PDAs), etc. for amplifying an RF signal for transmission by an antenna coupled thereto. In certain cases, the output power provided by the RF power amplifier has to be well-controlled (e.g., due to the specifications of the communication system for which the RF signal is transmitted).
To control the output power, a power detector can be used to determine an amount of power provided by the power amplifier. Conventional power detectors can properly determine the output power only when the antenna has a fixed load impedance. In practice, however, the antenna undergoes load impedance variations (e.g., due to a change in ambient temperatures, deterioration due to age, direct touch of a human body to the antenna, etc.). Such load impedance variations cause impedance mismatches between the RF power amplifier and the antenna, which in turn, cause the output power provided by the RF power amplifier to be reduced. These load impedance variations are not taken into account by conventional power detectors. Thus, conventional power detectors do not accurately determine the true power provided by the RF power amplifier.